Refrigerating machine of the absorption type



Nov. 26, 1929. G. MAIURI ET AL REFRIGERATING MACHINE OF THE ABSORPTIONTYPE Filed April 25, 1929 I Iiibnl'brs Maid/7'2 30,011; 2? 52mm UMfltzbrnevx.

Patented Nov.26,1929

UNITED STATES PATENT; OFFICE REFRIGERATING MACHINE OF THE ABSORPTIONTYPE Application filed April 25, 1929, SerialNo. 358,091, and at GreatBritain September 29, 1927.

Our invention relates to improvements in refrigerating machines of thekind in which evaporation and absorption of the refrigerant takeplaceinto and from an inert gas under pressure to compensate the pressureaccording to Daltons law.

The object of the invention is to provide an absorption refrigeratingmachine of the above described kind wherein the inert gas is introducedand sealed in the machine at atmospheric pressure. v

The above object is attained, according to the invention, by arrangingthat the volumetric capacity of the space in which the inert gascirculates in a closed circuit is less than the volumetric capacity ofthe vapour space in the boiler and condenser, whereby displacement ofinert gas from the boiler by refrigerant vapour increases the pressureof the inert gas to a pressure which, in conjunction with the pressureof the vapour, can eflect the liquefaction of the refrigerant.

In order that our invention may be properly understood and readilycarried into cffeet, we have hereunto appended one sheet of drawings, ofwhich Figure 1 is a View of one form of apparatus illustrating ourinvention.

Figure 2 is a similar view of a slightly modified form of construction.

It is to be understood that the machine can be constructed in differentforms to that illustrated. V

In carrying out our invention, and referring to Figural of the drawings,we provide a boiler 1 in the form of a coil or other formation, in whichthe rich ammonia solution is heated for the purpose of driving off.ammonia vapour; 2 is the space above the boiler in which the hot ammoniavapourpasses before going to the condenser 3. In this condenser 3 thegases are cooled by water which circulates in the annular space 4;therein the ammonia vapour is liquefied and passes therefrom by means ofa small siphon tube 5 into the refrigerating coil 6 where it evap oratesagain, so producing cold.

The ammonia vapour produced in the refrigerating coil becomes absorbedagain by the weak solution which passes into the absorber 7 representedin the figure as a horizontal pipe, which can however be constructed asa horizontal or helicoidal coil, as Will be hereinafter described.

In order to render the apparatus operative, it is necessary tocompensate the difference of pressure between the pressure necessary forthe liquefaction. of the ammonia, which liquefaction takes place at thetemperature of the cooling water in the-condenser 3, and the evaporatingpressure at low temperature in the refrigerating coil 6.

This iseifected in the following manner The machine is charged withammonia solution at the density necessary to obtain the best results upto the level 8-8, which is slightly above the level of the bottomsurface of the absorber 7. By so doing'the absorber 7 becomes partlyoccupied by liquid, the upper portion remaining occupied by air. Theapparatus is hermetically closed at this stage.

When the heating operation is started the ammonia vapour whichis drivenoff in the boiler, formed'by the coil 1, ascends in the space 2 and fromthere passes into the condenser 3, expelling the air through the smallpipe 5, and driving same into the pipes 6, 7, 9 and 10; if the spaces 2and 3 have a capacity six times that of the circuit formed by the pipesenumerated, when the ammonia vapour has expelled all the air from suchspaces 2, and 3, the pressure in the whole apparatus will be at 7 atms.

By continuing the heating, the pressure will be continuously augmenteduntil it will be a little superior to the pressure of liquefaction ofthe ammonia at thetemperature of the cooling water in the condenser 3.If, for instance this pressure is 10 atms., there will be in the circuitof the pipes 6, 7, 9 and 10 7 atms. of air pressure and 3 atms. ammoniavapour pressure.

In this condition the liquid ammonia, which by the inverted siphon ortrap 5 is conveyed to the evaporator coil 6, can evaporate at thetemperature of 10 C. on the evaporation being rendered possible byeffective removal of the ammonia vapour by absorption as soon as formed.

The relations between the capacities are calculated so as to obtain thebest functioning of the apparatus in relation to the temperature of thecooling water available and in relation to the minimum temperature whichis r uired in the refrigerating coil.

As descfibed in the specification of Patent No. 1,725,658,granted-August 20, 1929, of which we are co-patentees, to promote theremoval of the ammonia vapour by absorption, mixture of inert gas andammonia vapour which fills the pipes 6, 7 9 and 10 is forced tocirculate sufficiently by the thermosiphonic action which is obtained byheating the mixture in the vertical pipe 9 bycontact of the hot ammoniavapour from the boiler, and by cooling the same in the inclined pipe 10in contact with the water of the condenser. By suitably dimensioning thelength of this pipe 10, this circulation can be accelerated as required.

This forced circulation is suflicient to obtain a good evaporation inthe refrigerating coil because therein the ammonia vapour is generatedat a pressure which-tends to make it mix with the other gas, but suchforced circulation is not normally sufficient in the absorber where theweak liquor absorbs obviously only the ammonia which comes into.

contact with it.

To render the forced circulation eflicient as regards the absorption, itis necessary that the gases should circulate in the absorber in aturbulent manner, in order to increase their contact with the weakliquor.

The desired turbulence is set up in the pipe 7 forming the absorber, bythe gases flowing in the upper space thereof above the liquor in adirection opposite to that in which the weak li uor which flows alongthe bottom, the resdlting fluid friction sets the gas mixture inturbulence and causes more thereof to come into contact with the liquid,which latter absorbs the ammonia and rejects the air. The near]horizontal position of the pipe 7 tends to eep the gas mixture incontact with the liquid as long as possible, whilst however assuring acontinuous flow.

In our apparatus the circulation of the liquid takes place bythermosiphonic action in the ordinary way by the heat produced in theboiler and the cooling exchanger, which is in an inclined sition and inwhich in the part 11 the hquid is cooled and descends whilst in the-tube12 itis heated and ascends.

The liquid circulation passes through, the pipe 13 which leads the weakliquor intothe absorber 'i'. This pi' e 13 extends'througgh the casin14, in whic water circulates; thus complete y coolin the liquid beforeentering into the absor er.

The absorber 7 which we represent as a simple pipe can also have theform of a horizontal coil.

obtained in the by a helicoidal coil and the condenser 3 is also formedby a helicoidal coil. The exchanger, instead of being formed of twoconcentric pipes is formed by a pipe 11 in which is contained ahelicoidal coil 12, and in which the liquor is heated in ascending andis cooled and descends in the tube 11.

The apparatus represented in Figure 2 is intended or being worked byelectric heating by an electric resistance 19 wound round the verticalboiler 1. The apparatus is also: designed to work by air cooling and sono' water jackets are provided as in Figure 1. There is also provided anexchanger of temperature 1516, in the circuit of the inert gas, asdescribed in our said patent and a circulation by reverse flow of theliquid ammonia in the refrigerating coil 6, which descends by gravitywhilst the inert gas moves in the opposite direction, ascending. This isonly possible by the forced circulation obtained by the heating device.

The evaporation will occur with perfect efiiciency with this counterflowdisposition. The siphon 18, eliminates any excess of liquid ammoniawhich may tend to accumulate in the coil and also the water carried bythe ammonia vapour.

From the exchanger, the inert gas, rich with ammonia vapour, passesthrough the pi e 17, into the absorber 7.

aving now particularly described and ascertained the nature of our saidinvention and in what manner the same is to be performed, we declarethat what we claim is 1. An absorption refrigerating machine of the kindin which evaporation and absorption of the refrigerant take place intoand from an inert gas, in which the inert gas is sealed in the machineat atmospheric pressure, comprising a generator, a condenser, anevaporator, an absorber and conduits therebetween having the volumetriccapacity .of said evaporator, absorber and connecting conduits 1n whlchthe inert gas clrculates of char ing. the a paratus with liquid. GUf

DO MAIURI. RAOUL FELICE BOSSINI.

The apparatus shown in Figure 1 is dia-

